{"id":"F2006B02791","name":"AD/B727/87 Amdt 2 - Auxiliary Body Fuel System","slug":"ad-b727-87-amdt-2-auxiliary-body-fuel-system","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":42133,"registerId":"commonwealth-F2006B02791-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/B727/87 Amdt 2 - Auxiliary Body Fuel System","content":"COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n![](image.001.png)  \nBoeing 727 Series Aeroplanes\n\nAD/B727/87\n\nAmdt 2\n\n  \nAuxiliary Body Fuel System 10/95\n\nApplicability: All models with auxiliary fuel system installation.\n\nRequirement: Unless previously carried out action in accordance with Boeing Alert Service Bulletin 727-28A0062 Revision 5.\n\nNote: FAA AD 80-02-01 R2 Amdt 39-3969 supersedes Amdt 39-3864 which superseded Amdt 39-3864.\n\nCompliance: Within 500 flight cycles from 14 September 1995.\n\nBackground: Testing and inspection of the auxiliary body fuel system is required to prevent cell collapse and subsequent unscheduled transfer of fuel into the auxiliary tank.\n\nInstallation of the Boeing final design refuel and vent line shrouds constitutes terminating action for this AD.\n\nAmendment 2 mandates replacement of the fuel tank cap assembly prior to 500 cycles on any auxiliary fuel tank assembly that has been deactivated.","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":true,"description":"Amendment 2 expands the set of mandatory actions by adding a requirement to replace the fuel tank cap assembly on any auxiliary fuel tank assembly that has been deactivated, to be completed prior to 500 flight cycles. The original directive required testing and inspection and allowed a terminating fix by fitting the Boeing refuel and vent line shrouds; Amendment 2 adds a specific replacement obligation for deactivated tanks (Amendment 2, Requirement, Compliance)."},"complexity_factors":["Technical maintenance actions referenced by an external Boeing Service Bulletin (requires operator access to and interpretation of that bulletin) (Requirement)","Flight-cycle based compliance deadline (operators must track flight cycles from a specific date) (Compliance)","Availability of a terminating action (installation of shrouds) that changes long-term obligations (Installation)","An amendment adding a discrete mandatory replacement for deactivated tanks (Amendment 2)","Cross-reference to FAA AD history (Note) which may require administrative cross-checking"],"plain_english_summary":"What this directive does, in plain language:\n\n- This Airworthiness Directive applies to every Boeing 727 that has an auxiliary fuel system installed (\"Applicability\").\n- It requires operators to carry out the actions set out in Boeing Alert Service Bulletin 727-28A0062 Revision 5, unless those actions have already been done (\"Requirement\").\n- Specifically, the directive requires testing and inspection of the auxiliary body fuel system to avoid collapse of an auxiliary fuel cell and the unintended movement of fuel into that tank (\"Background\").\n- If operators install the Boeing final design refuel and vent line shrouds, that installation counts as a terminating action for this directive (i.e. no further action under this AD will be required once those shrouds are fitted) (\"Installation of the Boeing final design refuel and vent line shrouds constitutes terminating action for this AD\").\n- Amendment 2 adds a further mandatory action: if an auxiliary fuel tank assembly has been deactivated, the fuel tank cap assembly on that deactivated tank must be replaced before the tank has been used for 500 flight cycles (\"Amendment 2 mandates replacement of the fuel tank cap assembly prior to 500 cycles on any auxiliary fuel tank assembly that has been deactivated\").\n- All required actions must be completed within 500 flight cycles counted from 14 September 1995 (\"Compliance\").\n- The Note records an FAA Airworthiness Directive history relevant to this AD (\"Note\").\n\nWho is affected and who pays:\n\n- Affected parties: owners and operators of Boeing 727 aircraft equipped with auxiliary fuel systems (\"Applicability\").\n- Who pays: the aircraft owners/operators who must perform the inspections, testing, replacements, or install the terminating shrouds (the directive requires them to do the work; the text does not allocate funding or compensation) (\"Requirement\", \"Installation\", \"Amendment 2\").\n\nHow it works mechanically (what must be done and when):\n\n- Perform the inspections and testing specified in Boeing Alert Service Bulletin 727-28A0062 Revision 5, unless already done (\"Requirement\").\n- Complete required work within 500 flight cycles from 14 September 1995 (\"Compliance\").\n- Installing the Boeing refuel and vent line shrouds is an alternative that ends the need for further action under this AD once fitted (\"Installation...\").\n- For any auxiliary tank that has been deactivated, replace the fuel tank cap assembly before that tank reaches 500 flight cycles (\"Amendment 2\").\n\nStated purpose and practical effects:\n\n- Stated purpose: to prevent collapse of auxiliary fuel cells and subsequent unscheduled transfer of fuel into the auxiliary tank (\"Background\").\n- Practical effects: operators must schedule and carry out inspection and maintenance work within a fixed flight-cycle window, or install the specified shrouds as a terminating fix. Amendment 2 increases the set of mandatory maintenance acts by requiring cap replacement on deactivated tanks within the same flight-cycle limit (\"Amendment 2\" and \"Compliance\").\n\nIncentives, costs, compliance burden and discretion:\n\n- Incentives: completing the Service Bulletin actions or installing the terminating shrouds removes the need for further AD-mandated work for this issue (operators are incentivised to adopt the terminating design if it is cost-effective) (\"Requirement\", \"Installation\").\n- Direct compliance costs: inspection, testing, replacement of parts (including the fuel tank cap assembly for deactivated tanks), and possible downtime while the aircraft are out of service. The AD text does not quantify costs (only prescribes the work) (\"Requirement\", \"Amendment 2\").\n- Timing burden: all required actions are on a fixed schedule tied to flight cycles (500 cycles from 14 September 1995), so operators must track cycles and plan maintenance within that window (\"Compliance\").\n- Discretion: limited. The AD prescribes either compliance with the specified Service Bulletin or installation of the terminating shrouds; it does not offer alternative compliance paths in the text provided (\"Requirement\", \"Installation\").\n- Implementation risk and opportunity cost: operators face the immediate resource and scheduling cost of compliance; installing the terminating shrouds may require parts and fitment work but stops further AD actions for this issue (\"Installation\").\n\nNotes and cross-references:\n\n- The AD text includes a Note pointing to the FAA AD history that is relevant background and may affect related compliance records (\"Note\").\n\nKey source citations (from the AD text):\n- Applicability: \"All models with auxiliary fuel system installation.\" (Applicability)\n- Required action: \"Unless previously carried out action in accordance with Boeing Alert Service Bulletin 727-28A0062 Revision 5.\" (Requirement)\n- Compliance window: \"Within 500 flight cycles from 14 September 1995.\" (Compliance)\n- Safety rationale: \"Testing and inspection of the auxiliary body fuel system is required to prevent cell collapse and subsequent unscheduled transfer of fuel into the auxiliary tank.\" (Background)\n- Terminating action: \"Installation of the Boeing final design refuel and vent line shrouds constitutes terminating action for this AD.\" (Installation)\n- Amendment 2 addition: \"Amendment 2 mandates replacement of the fuel tank cap assembly prior to 500 cycles on any auxiliary fuel tank assembly that has been deactivated.\" (Amendment 2)\n- Regulatory cross-reference: \"Note: FAA AD 80-02-01 R2 Amdt 39-3969 supersedes Amdt 39-3864 which superseded Amdt 39-3864.\" (Note)\n\nSummary sentence: Owners/operators of Boeing 727s with auxiliary fuel systems must complete prescribed inspections and any required repairs or replacements specified in Boeing Alert Service Bulletin 727-28A0062 Rev 5 within 500 flight cycles from 14 September 1995, or fit the Boeing final design refuel and vent line shrouds as a terminating fix; Amendment 2 also requires replacement of the fuel tank cap assembly on any deactivated auxiliary tank before 500 cycles (\"Requirement\", \"Installation\", \"Amendment 2\", \"Compliance\")."},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This amendment maintains the original scope of addressing auxiliary body fuel system safety on Boeing 727 aircraft. Amendment 2 adds a specific requirement for deactivated fuel tanks (cap assembly replacement) but this is a logical extension of the safety regime rather than scope creep. The directive remains tightly focused on its original purpose."},"complexity_factors":["Single, specific aircraft type and system (Boeing 727 auxiliary body fuel system)","Only 2 main compliance requirements (inspection/testing per service bulletin, plus cap replacement for deactivated tanks)","Clear termination condition (installation of final design shrouds)","Simple time-based compliance trigger (500 flight cycles from fixed date)","No nested definitions or extensive cross-referencing to other legislation","References external technical document (Boeing Service Bulletin) rather than creating complex regulatory machinery"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** — essentially a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA) for specific aircraft.\n\n**What it does:**\nThis directive applies to **Boeing 727 aircraft** that have an auxiliary fuel system installed in the fuselage (body) of the plane. It requires owners and operators to take specific safety actions to prevent a dangerous fuel system failure.\n\n**The safety problem:**\nThe auxiliary body fuel system needs inspection and testing because there's a risk of **\"cell collapse\"** — meaning the fuel tank structure could fail or deform. If this happens, fuel could unexpectedly transfer into the auxiliary tank, creating potential fire hazards or balance problems for the aircraft.\n\n**What must be done:**\n- Aircraft operators must follow **Boeing Alert Service Bulletin 727-28A0062 Revision 5** — this is a manufacturer-issued technical instruction for fixing the problem\n- The work must be completed **within 500 flight cycles** (roughly 500 takeoff-landing trips) starting from 14 September 1995\n- **Amendment 2 adds a new requirement:** If an auxiliary fuel tank has been deactivated (taken out of use), the fuel tank cap assembly must be replaced before the aircraft completes 500 flight cycles on that deactivated tank\n\n**Permanent fix:**\nInstalling Boeing's final design for **refuel and vent line shrouds** (protective covers for fuel lines) counts as a permanent solution that ends the need for ongoing compliance with this directive.\n\n**Who it affects:**\nAnyone operating Boeing 727 aircraft in Australia with auxiliary body fuel tanks installed — primarily cargo operators and some older passenger services still flying this aircraft type in the mid-1990s."}},"importantCases":[],"_links":{"self":"/api/acts/ad-b727-87-amdt-2-auxiliary-body-fuel-system","history":"/api/acts/ad-b727-87-amdt-2-auxiliary-body-fuel-system/history","analysis":"/api/acts/ad-b727-87-amdt-2-auxiliary-body-fuel-system/analysis","conflicts":"/api/acts/ad-b727-87-amdt-2-auxiliary-body-fuel-system/conflicts","importantCases":"/api/acts/ad-b727-87-amdt-2-auxiliary-body-fuel-system/important-cases","documents":"/api/acts/ad-b727-87-amdt-2-auxiliary-body-fuel-system/documents"}}